Upgrading of bauxites, bauxitic clays, and aluminum mineral bearing clays

ABSTRACT

A process for the upgrading of aluminum mineral bearing raw materials by using at least three beneficiation treatment stages consisting of dispersion of a pulp of the material in specific pH ranges, screening in specific mesh sizes, and using at least one stage of high intensity magnetic separation.

BACKGROUND OF THE INVENTION

This invention is a continuation-in-part of my pending U.S. PatentApplication Ser. No. 838,445, filed Oct. 4, 1977, now U.S. Pat. No.4,193,791, which is a continuation-in-part of Ser. No. 736,466, filedOct. 28, 1976, now U.S. Pat. No. 4,113,466, granted Sept. 12, 1978, andmy pending U.S. Patent Application Ser. No. 115,397, filed Jan. 24,1979.

This invention is primarily applicable to the upgrading of bauxites,bauxitic clays, and aluminum mineral bearing clays. The conventionalmethod used for the upgrading of bauxites; reference American Instituteof Mining and Metallurgical Engineers, technical paper by AlcanInternational personnel presented at the 1977 Annual Meeting, Atlanta,Ga., Mar. 6-10, 1977; is to first crush the raw material to a specificsize, normally three inches, followed by wet screening at 20 mesh Tyler,retaining the plus 20 mesh size fraction as the upgraded bauxite, andthe minus 20 mesh portion is rejected as waste. The upgrading in thiscase is mainly to reduce the silica in the plus 20 mesh product togetherwith some removal of the iron and titanium minerals. The amount rejectedas waste is usually a minimum of 40 percent of the original feedmaterial and contains a relatively high percentage of the desirablealuminum bearing minerals which have the chemical analysis of Al₂ O₃.xH₂O. In the treatment of clays, in which one of the main uses is for therefractory industry, to the knowledge of the inventor, the only majorupgrading that is done on a commercial basis is the use of high magneticintensity separators using steel wool as the magnetic media primarilyfor the reduction of the iron content of the raw material. Such magneticseparators are of the type manufactured by the Sala Company of Sala,Sweden. In using steel wool as a magnetic media, the product must bereduced in size to essentially minus 10 microns, which is difficult andexpensive; otherwise any granular material essentially coarser than 10microns hangs up in the steel wool and entails large losses of thedesirable portion of the raw material. In addition, only small amountsof magnetically susceptible material can be economically removed due tothe limited amount of magnetics that can be held by the steel wool oralternately, only small tonnages of material can be treated by such ahigh-intensity magnetic unit entailing high capital costs per ton ofmaterial treated.

In applying my invention to the upgrading of bauxites, and by the use ofa number of low cost beneficiation stages, I have been able to use ahigh intensity magnetic separator of the Jones type which entails theuse of no specific type of magnetic media such as steel wool, allowingme to remove large quantities of magnetically susceptible minerals andin particular iron and titanium minerals from the original feed materialat a comparatively low cost. Further, if necessary, I use a deslimingstage at preferably 2.0 to 10.0 microns, the combination of whichupgrades the original bauxite to an appreciably higher grade than washeretofore possible by the elimination of large amounts of the iron andtitanium minerals together with silica, resulting in an appreciablyhigher grade bauxite than was heretofore economically possible togetherwith an appreciable increase in recovery of the desirable Al₂ O₃.xH₂ Ominerals, where x is the amount of water chemically combined with theAl₂ O₃.

In the treatment to upgrade clays, I use a number of novel low costbeneficiation steps including the Jones type magnetic separator, toremove a major portion of the iron and titanium minerals with but minorlosses of the desirable aluminum bearing minerals, which in this caseare normally predominantly Kaolinite, of which the chemical analysis isAl₂ O₃.2SiO₂.2H₂ O.

SUMMARY OF THE INVENTION

It is accordingly a primary object of the present invention to provide anovel process for the upgrading of bauxites by reducing at least theiron and titanium content of the original material and in most cases,also the percentage of silica. It is a further object of the presentinvention to provide a novel and low-cost process for the upgrading ofbauxitic clays and clays to produce a product that is appreciably lowerin iron and titanium analysis than the original feed material togetherwith comparatively low losses of the desired contained aluminum bearingminerals. Other objects and advantages of the claimed invention willbecome apparent as the description thereof proceeds.

In satisfaction of the foregoing objects and advantages there ispresented by this invention in its broadest concept a process for theupgrading of bauxites, bauxitic clays, and clays in which at least theiron and titanium minerals are appreciably reduced, and in the case ofthe bauxites, the silica content is also appreciably reduced, theprocess comprising:

(a) Preparation of the raw material--in the treatment of raw materialssuch as bauxite and bauxitic clays, the normal circuit will consist ofcrushing to a sufficiently small feed size suitable for furtherreduction in such comminution units as a rod mill or ball mill. Suchfeed size will normally be minus 3/4 inch. In my preferred circuit, Iuse a pulp density for at least one wet grinding stage of 40 to 55percent solids and maintain the pH at the discharge of the said at leastone wet grinding stage of at least 8.5, using at least sodium hydroxideas the alkaline agent. Where I use NaOH as the alkaline agent along orin combination with other alkaline agents selected from the groupconsisting of KOH, NH₄ OH, and Na₂ CO₃, my pH range is about 9.5 toabout 12.5. Where I use at least NaOH as the alkaline agent incombination with a dispersing agent selected from the group consistingof lignins, silicates, and phosphates, my pH range in the at least onewet grinding stage is in the pH range of about 8.5 to 12.5. By thismeans I obtain controlled dispersion of the solid particles in the pulpwhich results in high efficiencies of grinding by being able to operateat a comparatively high pulp density level, resulting in low powerconsumption and excellent liberation characteristics of the variouscontained minerals, again which results in the ability of the subsequenthigh intensity magnetic stage to remove a large percentage of themagnetically susceptible iron and titanium minerals with a comparativelylow loss of the aluminum bearing minerals which are nonmagnetic.

In treating such raw materials as clay, which may contain only smallamounts of coarse material or a negligible amount, I prefer to form apulp of the original material in the pulp density range of about 10percent solids to about 55 percent solids using at least sodiumhydroxide as the alkaline and dispersing agent and controlling the pulppH in the range of about 9.5 to 12.5, or alternately, as noted above,using sodium hydroxide either in combination with other alkaline agentsor sodium hydroxide alone in combination with dispersants, oralternately, sodium hydroxide in combination with other alkaline agentsand dispersants.

(b) Following the at least one wet grinding stage, I prefer to screenthe material to within the range of 10 mesh to 65 mesh Tyler. Theoversize fraction from the screening operation may either be sent towaste which would normally consist of wood contained in the originalmaterial or alternately return part or all of the oversize fraction tothe at least one wet comminution stage. The mesh size that I use in thisstage will be dependent upon the subsequent processing steps. If I use alow to medium high magnetic separation step in which the magneticseparators are of the conventional drum type using either permanent orelectromagnetics in which the magnetic field strength is in the range ofabout 0.5 to 10.0 kilogauss, my preferred screen size is in the range ofabout 10 to 35 mesh. Further, I may omit any screening stage prior tosuch magnetic cobbing.

If the screen undersize is fed directly to my at least one high magneticintensity separation stage, my preferred screen size is about 20 mesh to65 mesh Tyler.

If I subsequently use a desliming step prior to any magnetic separation,I may use one or more screening stages prior to or after desliming.

(c) High intensity magnetic separation stage--in this stage I prefer touse a pulp density of about 15 percent to 45 percent solids maintainingthe pH of the pulp with at least an alkaline agent and in the pH rangeof 8.5 to 12.5.

In applying my invention to bauxites, I prefer to follow this stage witha desliming step.

(d) Desliming--in the simplest application of the invention, I prefer todeslime the material at a particle size of about 2 to about 10 micronsusing conventional equipment such as thickener-sizer separators,hydroseparators, or centrifugal separators, all well known in the art.The minus fraction from such treatment will normally contain a muchhigher percentage of the silica than in the original material togetherwith appreciably higher amounts of both iron and titanium minerals thanwas contained in the original material, thus upgrading the plus fractionwhich will be impoverished in iron, titanium, and silica than waspresent in the original feed material.

Prior to such desliming, I may remove a coarser fraction from thematerial prior to such treatment by using one or more stages of cyclonesin which the plus fraction may be as coarse as essentially plus 200 meshwhile the essentially minus 200 mesh fraction is feed to the abovedescribed desliming stage.

In the application of the invention to clays, I do not normally use thedesliming stage as the losses of the desirable aluminum bearing mineralsare too high to be economically feasible.

(e) In the case of the bauxites, following the desliming stage, I preferto treat at least the plus fraction in at least one additional highmagnetic intensity step using the Jones type separator and magneticfield strength in the range of about 11.0 to 22.0 kilogauss. Dependenton the economics, I may also use the steel wool type magnetic separatoron the minus 2 to about minus 10 mesh fraction to remove residual ironand titanium and combining this nonmagnetic fraction with thenonmagnetic fraction from the plus portion of the separation, oralternatively, this minus fraction may be fed to such a process as theBayer Process for the aluminum mineral recovery or alternately, havecommercial value in the aluminum chemical products industry.

The following will define for clarity various terms used in describingthe invention:

Magnetic Cobbing--passing a prepared pulp of the material through amagnetic field to remove from the material a magnetic concentratecontaining a large percentage of the iron and titanium minerals which isrejected as waste, and nonmagnetic product that analyzes appreciablylower in iron and titanium than the original feed material, andcontaining a high percentage of the original aluminum minerals containedin the material.

Desliming--separation of the fine particles of the prepared materialfrom the coarser fraction.

In the practice of my invention this separation is usually carried outat 2.0 to 10.0 microns, with the minus fraction to waste or some otheruse such as the Bayer Process, and the plus 2.0 to plus 10.0 microns asthe retained product for subsequent processing or commercial use. Thisdesliming step is only carried out where a relatively high percentage ofthe iron and titanium minerals in the minus 2.0 to minus 10.0 micronsized ranges will not respond to high magnetic intensity cobbing and theloss of aluminum minerals in this product is either economicallyacceptable, or that little or no loss of the aluminum minerals takesplace where such product can be economically fed to a Bayer Process.

Bauxites and bauxitic clays--there is a thin line in these definitions.The difference between bauxites and bauxitic clays is essentially thepercentages of Al₂ O₃.xH₂ O minerals contained in the materials. Wherepractically all of the silica in these materials is present asKaolinite, the relative percentages of silica are taken as thedefinitive separation point.

For instance, Arkansas bauxites can be defined as containingapproximately less than 16 percent SiO₂, and Arkansas bauxitic clays,more than 16 percent SiO₂.

Clays--generally refer to materials containing little or no Al₂ O₃.xH₂ Ominerals and the major aluminum mineral component is essentiallykaolinite, Al₂ O₃.2SiO₂.2H₂ O.

Alumina--Al₂ O₃.

Iron and titanium--the standard practice of the aluminum industry is toreport Fe and Ti analyses as Fe₂ O₃ and TiO₂. The iron and titaniumminerals contained in the aluminum bearing materials vary considerablyand are but rarely only in the form of Fe₂ O₃ and TiO₂. For instance,the major iron mineral in Arkansas bauxite is siderite, FeCO₃, and thecommonest occurring form of titanium is as ilmenite, FeOTiO₂. When Irefer to percentages of Fe₂ O₃ and TiO₂ herein, I mean the chemicalanalyses as Fe and Ti converted to Fe₂ O₃ and TiO₂, respectively.

Alkaline agent--an agent used to raise or maintain the pH of the pulpwithin certain optimum pH ranges. The alakline agents that may be usedin this process are alkaline dispersing agents selected from the groupconsisting of sodium hydroxide, potassium hydroxide, ammonium hydroxide,sodium carbonate, and mixtures thereof as described herein.

Dispersing agents--families of dispersants such as lignins, phosphates,silicates, or any other family of specific dispersants which may beeconomically used to disperse the solids contained in the pulp of theraw material, and which, in combination with at least one alkalineagent, sodium hydroxide, in specific pH ranges, combines to result inthe unique and outstanding metallurgical results in removing iron andtitanium minerals from the material by high intensity magneticseparation.

In combining one or more dispersing agents with at least sodiumhydroxide as the alkaline agent I have found that for optimum results inremoving iron and titanium minerals from the feed material by highintensity magnetic separation, I require the pH of a pulp of thematerial to be raised to at least 8.5 using at least sodium hydroxide asthe alkaline agent and preferably at an optimum pH point in the range of9.5 to 12.5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the use of high intensity magnetic separation as the first majorprocess step in removing a high percentage of the contained iron and/oriron and titanium from the feed material, the preparation of the feedmaterial prior to the magnetic separation circuit is important.

If the original feed material is too coarse a size as feed to acomminution unit such as a rod mill or ball mill, I firstly crush and ifnecessary screen and feed material to the appropriate size and feed itto at least one stage of wet grinding. To this at least one stage ofgrinding I add at least sodium hydroxide as a combined alkaline anddispersing agent, controlling the pH of the pulp discharge from thegrinding unit preferably within the pH range of 9.5 to about 12.5. If Icombine dispersing agent with at least NaOH as the alkaline agent I mayreduce the lower end of the pH range to about 8.5. By this means Iobtain high efficiency in my grinding circuit using pulp densities ashigh as 60 percent solids, with good liberation of the magneticallysusceptible minerals, and in particular, the iron and titanium minerals.

Without the above noted use of alkaline agents either alone or incombination with dispersing agent, it would be impossible to operate atsuch high densities with many of the aluminum bearing materials.

My preferred range of pulp density in the at least one wet grinding millis 45 percent to 55 percent solids.

Following the at least one wet grinding mill I prefer to dilute the pulpto 15 percent to 45 percent solids dependent on the pulp density Isubsequently use to the first stage of high intensity magneticseparation. Following the dilution of the pulp I prefer to screen thesolids using one or more screens in the range of 20 to 65 Tyler mesh.The oversize from the screening circuit may be sent to waste containingmostly wood which occurs with the feed material, or alternately part orall of the oversize can be returned to the wet grinding circuit.

The undersize may be fed as is or further diluted to the at least onestage of high intensity magnetic separation.

My preferred range of pulp densities to this stage is in the range ofabout 15 to 45 percent solids. I prefer to use at least two stages ofhigh intensity magnetic separation. The magnetic concentrate orconcentrates may be sent to a thickener or tailings pond where thesolutions are recovered and recirculated to the magnetic or grindingcircuits, or alternately, the thickener underflow containing themagnetic concentrate or concentrates reground to liberate furtheraluminum bearing minerals which may be recovered by an additional stageor stages of magnetic separation treatment.

Following the magnetic circuit the nonmagnetic fraction of the feedmaterial may be sent to a thickener, followed by a filter or other meansof bulk solution removal such as centrifugal separator, and the filtercake or centrifugal cake sent to storage for partial air drying prior todrying and/or dehydration or directly to dehydration. Alternately, thenonmagnetic fraction may be subjected to a desliming operation usingconventional equipment such as cyclones, hydroseparators, andthickening-sizer apparatus such as is used in iron ore beneficiation andwell known in the art.

I only use a desliming circuit where substantial amounts of iron occurin the minus 2.0 to minus 10.0 micron size range and which iron-bearingminerals do not effectively respond to my magnetic separation circuit.Further, this desliming circuit involves a loss of some of the aluminumbearing minerals, and if such loss is too high it precludes the use ofthis circuit. If the losses in aluminum bearing minerals is withinacceptable economic limits, or the contained aluminum bearing mineralscan be used and treated in other processes such as the Bayer process,then there is economic justification for the use of this deslimingcircuit in treating specific materials.

There is a third alternative in treating the deslimed fraction of thefeed material and that is feeding it to a magnetic cobbing circuit usinga minimum field strength of 16.0 kilogauss and preferably in the rangeof about 18.0 to about 22.0 kilogauss. This high magnetic intensityfield combined with a special design of magnetic media such as theColbourn magnetic separator using steel balls, or the Sala type magneticseparator using steel wool, may remove sufficient of the contained ironand/or iron and titanium minerals to economically justify such amagnetic circuit with the nonmagnetic fraction combined with thenonmagnetics from the plus 2.0 to plus 10.0 micron sized fraction.

Following the desliming circuit, I may or may not use a further stage ofhigh intensity magnetic separation on the plus 2 to plus 10 micron sizedfraction. The use of such an additional stage is dependent upon theamount of residual magnetically susceptible iron and/or iron andtitanium minerals that can be removed and the economics of adding such astage to the overall circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference is now made to the accompanying drawings wherein:

FIG. 1 shows the simplest flow sheet of the invention;

FIG. 2 shows the simplest flow sheet of the invention in the treatmentof bauxite, bauxitic clays and aluminum mineral bearing claysincorporating at least one wet grinding stage in the dispersion stage;

FIG. 3 shows incorporation of the dispersion and grinding stages andshows an additional preferred stage of desliming; and

FIG. 4 shows a preferred flow sheet of the invention using thecombination of dispersion and wet grinding followed by screening, andafter screening, at least one stage of low to medium intensity magneticseparation prior to the use of at least one stage of high intensitymagnetic separation.

As may be understood from this disclosure and drawings, in its broadestembodiment, this invention provides a process for the upgrading ofaluminum mineral bearing materials selected from the group consisting ofbauxites, bauxitic clays, and aluminum mineral bearing clays comprisingthe steps of:

(a) subjecting a pulp of the said material to at least one dispersionstage in the presence of at least sodium hydroxide and in the pH rangeof about 8.5 to 12.5;

(b) subsequently subjecting the said pulp to at least one screeningstage in the range of 10 mesh Tyler to 65 mesh Tyler to produce a minus10 to minus 65 mesh product;

(c) subsequently subjecting said minus 10 to minus 65 mesh product to atleast one stage of high intensity magnetic separation using a fieldstrength of about 11.0 to 22.0 kilogauss to produce a magneticconcentrate enriched in iron and titanium minerals, and a nonmagneticproduct impoverished in iron and titanium minerals.

The following description of the drawings sets forth additional detailsand embodiments of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the simplest flow sheet of the invention. The applicationof this simplest flow sheet is primarily for the removal of iron andtitanium minerals from aluminum mineral bearing clays wherein thenatural grain size of the constituent minerals is at least finer than 10mesh. Such material will not require initial preparation, such ascrushing. The raw material would normally be fed to a mechanicalagitator using a ship type propeller (not shown) in which mill solutionor water would be added to form a pulp at numeral 10, within the pulpdensity range of 10 to 60% solids wherein at least sodium hydroxidewould be added and the pH controlled within the range of about 9.5 to12.5 to obtain dispersion of the contained solids. In one of thepreferred embodiments of my invention I prefer to use at least sodiumhydroxide as the alkaline agent in combination with a dispersantselected from the group consisting of lignins, silicates and phosphatesand in which the pH is controlled within the range of about 8.5 to 12.5.

Following formation of the pulp at this stage, at numeral 11, I screenthe material in the range of 10 mesh to 65 mesh Tyler. This screeningstage is important in the use of my subsequent stage of high intensitymagnetic separation wherein the magnetic gap (not shown), specificallythe Jones type magnetic separator, the strength of the magnetic fieldand the efficiency of the removal of the iron and titanium minerals isdependent upon the width of the magnetic gap used. Thus, my screen sizeis a function of the high intensity magnetic separator and itsefficiency. I have found that the screen size must be so chosen that themaximum sized particle passing through the screen should be at leastabout 10% less in dimension than the width of the magnetic gap setting.This use of a screen in such a beneficiation circuit is quite contraryto conventional practice where the screen size is normally determined bythe liberation characteristics of the valued mineral constituents. Thiscombination of the screen size and the width of the magnetic gap is oneof the features of the invention, particularly in combination with thedispersion stage ahead of both the screening and the at least one highintensity magnetic separation stage which allows me to operate both thescreening stage and the high intensity magnetic separation stage at pulpdensities as high as 45% solids which heretofore, were, to theinventor's knowledge impossible. By being able to operate with such highdensity, the residence time of the magnetically susceptible iron andtitanium minerals have an appreciably longer period of time in themagnetic field then was heretofore possible. By this means theefficiency of my high intensity separation circuit is outstanding.

Numeral 12 shows the oversize from the screening stage either reduced insize by a wet comminution unit, or a portion such as wood, rejected towaste, and the remaining portion ground to minus 10 mesh.

The undersize at 13 may be further diluted to within the range of about10 to 45% solids, and fed to the at least one stage of high intensitymagnetic separation, shown at 14, using a magnetic field strength of11.0 to 22.0 kilogauss. Following this stage the magnetic concentrate,shown at 15, consisting chiefly of iron and titanium minerals, wouldnormally be fed to a thickener shown at 17, with the thickener overflowat 18 returned as dilution to the magnetic separation and comminution ofraw material circuits. The underflow, shown at 19, from the thickener isthe magnetic concentrate containing chiefly iron and titanium mineralsand would normally be sent to waste.

The nonmagnetics, shown at 16, produced by the at least one stage ofhigh intensity magnetic separation would normally be sent to thickeningand filtering with the solutions, shown at numeral 20, from thickeningand filtering used as dilution to the magnetic separation andcomminution of raw material circuits. The filter cake shown at 21, isthe final upgraded aluminum mineral product.

FIG. 2 shows the simplest flow sheet of the invention as applied tobauxites, bauxitic clays, and aluminum bearing clays, shown at 22, andas mined or after conventional crushing, and/or washing and screeningprocedures. Numeral 23 of the flow sheet combines at least one wetgrinding stage with dispersion of the solids contained in the pulp. Thepreferred pulp density of this at least one wet grinding stage is 45 to55% solids with the minimum being approximately 25% solids and themaximum about 60% solids and in the presence of at least sodiumhydroxide with the pH maintained in the range of about 9.5 to 12.5.

Numeral 24 shows the screening stage following the at least one wetgrinding stage and numerals 25, 26, 27, 28, 29, 30, 31, 32, 33, and 34correspond to FIG. 1, numerals 12, 13, 14, 15, 17, 18, 19, 16, 20 and21, respectively, to result in the final product.

FIG. 3 incorporates all of FIG. 2 to numeral 32 inclusive and withoutthickening and filtering. From 35, this nonmagnetic product is fed, atnumeral 36, to desliming in which preferably the separation is made withconventional equipment, (not shown) and at 2 to 10 microns, and to ascoarse as 200 mesh Tyler. The undersize particles from this separation,shown at numeral 37, are enriched in iron and titanium minerals andwould normally be sent to waste. The oversize particles, shown atnumeral 38, are impoverished in iron and titanium minerals. This productmay be treated by either of two alternative procedures. In alternate(1), the oversized particles, shown at 39, are fed to at least one stageof high intensity magnetic separation using a minimum field strength of11.0 kilogauss with the magnetic concentrate produced, shown at numeral41, containing chiefly iron and titanium minerals. This product, shownat numeral 42, follows the same flow sheet as FIG. 2, numerals 29, 30and 31. In alternate (2), the nonmagnetic fraction shown at numeral 43is normally subjected thickening and filtering and as shown at numeral44, follows the same flow sheet as FIG. 2, numerals 33, 34.

FIG. 4, as shown at numeral 45, is the screen undersize as shown in FIG.2, numerals 22, 23, 24, 25 and 26, diluted to about 15 to 45% solids asshown at numeral 46, fed to at least one stage and preferably at leasttwo stages of low to medium intensity magnetic separation using magneticfield strengths of 0.5 to 10.0 kilogauss. The magnetic concentrateproduced, as shown at numeral 47, will be chiefly iron and titaniumminerals and as shown at numeral 48, will follow the flow sheet as FIG.2, numerals 29, 30, 31. The nonmagnetic fraction produced, as shown at49, will follow the flow sheet as FIG. 2, numerals 27, 28, 29, 30, 31,32, 33 and 34.

The following examples are presented to illustrate the invention, butthey are not to be considered as limited thereto. In these examples andthroughout the specification, parts are by dry weight unless otherwiseindicated.

EXAMPLES OF THE OPERATION OF THE INVENTION

In all of the following examples the ore as received was air dried forease of handling and put through a hammer mill to produce a product thatwas approximately minus three quarter inch.

For pilot plant operation this was the feed material to the single stageball mill grinding circuit that was used.

For laboratory research work the minus 3/4 inch product was furtherreduced to minus 6 mesh for grinding in a single stage laboratory rod orball mill.

EXAMPLE 1

This example is an illustration of employing a preferred embodiment ofmy invention in using at least one stage of high intensity magneticseparation.

The feed material was an Arkansas bauxite.

The major components of the pilot plant were a ball mill, followed by a35 mesh screen, a low intensity drum type magnetic separator, a Joneshigh intensity magnetic separator with reputed magnetic field strengthof 14 to 16 kilogauss, and means for thickening, filtering and materialshandling.

The feed rate to the ball mill circuit was 800 pounds per hour on a dryore basis.

NaOH was used alone as the alkaline agent and throughout all of thetests the pH was maintained at the ball mill discharge between 10.7 to10.9.

The dispersing agent was added to the feed end of the ball mill.

2080 is a lignin compound supplied by the Rayonier Company, a subsidiaryof ITT.

HMP is sodium hexametaphosphate.

Orzan is a trade name of Crown Zellerbach, and is a lignin compound.

Quebracho is a lignin, and a bark extract from South America.

Unless otherwise stated the solution strengths of all reagents used was21/2%, with the exception of NaOH which was a 10% solution.

In all cases the percent solids in the ball mill discharge wascontrolled at approximately 50% solids, and the % solids to the numberone high magnetic intensity stage of the Jones Magnetic Separator was 42to 44%.

The screen oversize was sent to waste as it contained mainly wood.

The drum type magnetic cobber was of low kilogauss strength and notmeasured. It removed less than 0.2% of the original feed as magneticparticles.

The Jones Magnetic Separator, supplied by Klockner Humboldt Deutz ofCologne, Germany, had an upper and lower magnetic ring.

In the following tests 2 magnetic cobbing stages were made on the topring and one magnetic cobbing stage on the lower ring, for a total ofthree magnetic separation stages.

The following results were obtained with the major variable being theDispensing Agent.

    ______________________________________                                        Dis-   % - Chemical Analysis and % Wt.                                        persing                                                                              Magnetic Concts. Non Magnetics                                         Agent                      %                    %                             lbs./Ton                                                                             SiO.sub.2                                                                            Fe.sub.2 O.sub.3                                                                      TiO.sub.2                                                                          Wt.  SiO.sub.2                                                                          Fe.sub.2 O.sub.3                                                                    TiO.sub.2                                                                          Wt.                           ______________________________________                                        2080                                                                          3.97   11.0   23.7    5.2  19.2 17.8 1.69  1.35 81.8                          lbs/Ton                                                                       HMP                                                                           1.0    9.3    31.2    5.4  16.7 18.0 1.85  1.50 83.3                          lbs/Ton                                                                       HMP                                                                           1.0    10.4   26.9    5.5  16.1 17.9 1.67  1.45 83.9                          lbs/Ton                                                                       and                                                                           Que-                                                                          bracho                                                                        0.75                                                                          lbs/Ton                                                                       Que-                                                                          bracho                                                                        1.06   9.6    27.9    5.4  15.6 18.0 1.81  1.46 84.4                          lbs/Ton                                                                       and                                                                           Orzan                                                                         0.61                                                                          lbs/Ton                                                                       ______________________________________                                         Note:                                                                         Average head analysis was 16.0% SiO.sub.2 6.2% Fe.sub.2 O.sub.3, and 2.0%     TiO.sub.2.                                                               

EXAMPLE 2

The following pilot plant run was made on an Arkansas Bauxitic Clayusing the same circuitry as in Example 1. The major difference was inthe % solids to the number one magnetic cobbing stage of the JonesMagnetic separator; this was 19.0% solids.

The Alkaline Agent was NaOH, and the pH in the circuit maintained at10.7 to 10.8, and the Dispersing Agent was Quebracho used at the rate of0.5 lbs/ton of ore.

The following results were obtained:

    ______________________________________                                        % Chemical Analysis and % Wt.                                                 Magnetic Concts.  Non Magnetics                                               SiO.sub.2                                                                           Fe.sub.2 O.sub.3                                                                      TiO.sub.2                                                                             % Wt. SiO.sub.2                                                                           Fe.sub.2 O.sub.3                                                                    TiO.sub.2                                                                          % Wt.                            ______________________________________                                        21.8  21.9    7.2     11.7  32.9  0.88  1.14 88.3                             ______________________________________                                         Note:                                                                         Head analysis of feed was 31.5% SiO.sub.2, 3.34% Fe.sub.2 O.sub.3 and         1.99% TiO.sub.2.                                                         

EXAMPLE 3

This example is an illustration of employing a preferred embodiment ofmy invention in using at least one stage of high intensity magneticseparation and at least one stage of desliming.

The ore used was a Bauxite from South America which had beenconventionally treated by crushing and washing out of the fines.

The head analysis was as follows:

    ______________________________________                                        Chemical Analysis - %                                                         SiO.sub.2 Fe.sub.2 O.sub.3                                                                          TiO.sub.2   P.sub.2 O.sub.5                             ______________________________________                                        4.0       8.1         1.0         0.12                                        ______________________________________                                    

600 grams of the dried material was ground in a laboratory rod mill at50% solids with 12 ccs of 10% NaOH and 6 ccs of 2080 for 8.0 minutes.Following the ball mill the pulp was conditioned for 15 minutes in aWemco cell with the pH adjusted to 12.0 with NaOH and then subjected totwo stages of magnetic cobbing in a laboratory size Colburn highintensity magnetic unit. The two magnetic concentrates were cleaned oncewith the cleaner tailings returned to the non-magnetic portion of thepulp.

The total non-magnetic portion was subjected to a desliming stage usinga thickener-sizer as the equipment.

The following results were obtained:

    ______________________________________                                                 Chemical Analysis - %                                                Product    %                                                                  Produced   Wt.      SiO.sub.2                                                                             Fe.sub.2 O.sub.3                                                                     TiO.sub.2                                                                           P.sub.2 O.sub.5                      ______________________________________                                        Magnetic                                                                      Concentrate                                                                              13.7     3.90    29.3   1.52                                       Deslime Product                                                               Minus 5 microns                                                                          13.6     9.40    19.7   3.20                                       Deslime Product                                                               Plus 5 microns                                                                           72.7     3.15    1.39   0.53  0.003                                           100.0                                                              ______________________________________                                    

As in Examples 1 and 2 the excellent metallurgical separation of theiron and titanium minerals with but minor losses in alumina are to benoted. In addition, these are low cost beneficiation steps.

EXAMPLE 4

This example is an illustration of employing a preferred embodiment ofmy invention in using at least one stage of high magnetic intensityseparation prior to desliming, a desliming stage, and finally at leastone stage of high magnetic intensity separation following desliming.

The ore used in this example was a Bauxite from Africa and had thefollowing analysis:

    ______________________________________                                        Chemical Analysis - %                                                         SiO.sub.2   Fe.sub.2 O.sub.3                                                                             TiO.sub.2                                          ______________________________________                                        1.09        6.59           2.95                                               ______________________________________                                    

600 grams of the material was ground for 5 minutes in a laboratory ballmill at 50% solids and a pH of 10.3 using 8 ccs. of 10% NaOH and 18 ccs.of 21/2% Quebracho solution. Following the grinding stage the pulp wastransferred to a Wemco cell and conditioned for 5.0 minutes with thepulp pH adjusted to 10.5 with NaOH.

The pulp was then given a single stage high magnetic intensity passthrough a Colburn laboratory unit and cleaned once with the cleanertailings combined with the non-magnetic fraction produced. The totalnon-magnetics were then deslimed at approximately 5 microns using alaboratory thickener-sizer unit.

The plus 5 micron sized fraction was then diluted to approximately 20%solids and subjected to two passes through the Colburn unit at highmagnetic intensity. The two magnetic concentrates were combined andcleaned once with the cleaner tailings combined with the non magneticfraction.

The following results were obtained:

    ______________________________________                                                   Chemical Analysis - %                                              Product      %                                                                Produced     Wt.      SiO.sub.2                                                                              Fe.sub.2 O.sub.3                                                                     TiO.sub.2                               ______________________________________                                        Magnetic Conct. 1                                                             Prior to Desliming                                                                         8.3      1.58     40.8   12.1                                    Deslime Product                                                               Minus 5 microns                                                                            19.8     1.42     8.8    3.5                                     Magnetic Conct. 2                                                             After Desliming                                                                            5.2      0.96     11.0   4.6                                     Deslime Product                                                               Plus 5 microns                                                                             66.7     0.85     1.57   1.53                                    ______________________________________                                    

The Deslime Product Minus 5 microns and the Magnetic Conct. 2 afterdesliming are suitable feed materials to the Bayer Process, while theDeslime Product plus 5 microns is an outstanding product for use in thechemical or refractory industries.

The magnetic Conct. 1, prior to desliming, would be a waste product.

EXAMPLE 5

This example is a preferred embodiment of my invention using in thebeneficiation circuit three stages of high intensity magnetic cobbing ina Jones magnetic separator to produce three magnetic concentrates thatwere combined and hereafter referred to as "Total Magnetic Concentrate",and a non magnetic product. The non magnetic product was fed to a highefficiency cyclone to produce two products, the "Cyclone Underflow"which was substantially plus 500 Tyler Mesh, and the Cyclone Overflowwhich in turn was fed to a centrifuge for desliming at approximately 5.0microns. Two products were produced from the centrifuge, and hereafterreferred to as "Centrifuge Minus 5 Microns" and "Centrifuge Plus 5Microns".

The ore used for this example was a bauxite from South America and wasparticularly high in iron content.

The ore was treated as mined without the normal screening and washingprocedures that eliminates, on a material of this type, about 40% ormore as waste.

The beneficiation circuit used was a continuous operating pilot plantinvolving a single ball mill in which the pulp density was 51% solids,the pH at the mill discharge maintained at 10.7 to 10.8 with NaOH, and0.6 lbs. Quebracho per dry ton of feed, and 1.0 lbs. Orzan per dry tonfeed were added to the ball mill intake.

Following the ball mill, the product was fed to a 28 mesh screen withthe oversize, mainly wood, to waste, and the undersize diluted to 28%solids and fed to a Jones High Intensity Magnetic Separator, followed by2 more passes through the separator. The three magnetic concentratesproduced were combined into the "Total Magnetic Concentrate". Thenonmagnetic product was fed to a high efficiency cyclone producing aCyclone Underflow containing about 75% plus 500 mesh and a CycloneOverflow that was approximately 85% minus 500 mesh.

The Cyclone overflow was fed to a Bird Centrifuge producing an underflowproduct essentially plus 5 microns and an overflow product essentiallyminus 5 microns.

The gap setting on the Jones Magnetic Separator was 0.50 to 0.60millimeters. The screen size preceding the magnetic separator was 35mesh. When using such a low gap setting the maximum sizing of myscreening stage is 28 mesh and preferably 35 to 48 mesh.

The following results were obtained:

    ______________________________________                                        Product      Chemical Analysis - %                                            Produced     % Wt.    SiO.sub.2                                                                              Fe.sub.2 O.sub.3                                                                     TiO.sub.2                               ______________________________________                                        Total Magnetic                                                                Concentrate  18.2     6.1      48.6   1.76                                    Centrifuge                                                                    Minus 5 Microns                                                                            15.0     19.2     28.2   5.83                                    Centrifuge                                                                    Plus 5 Microns                                                                             27.3     3.35     6.7    1.70                                    Cyclone                                                                       Underflow    39.5     2.7      2.8    0.92                                    Calculated                                                                    Heads        100.0    6.1      16.0   2.0                                     ______________________________________                                    

The "Total Magnetic Concentrate" and the "Centrifuge Minus 5 Microns"would be treated as waste.

The "Centrifuge Plus 5 Microns" is excellent feed to the Bayer Processand appreciably higher in recoverable alumina content thanconventionally crushed and washed Bauxite that is in planned productionfrom the same geological area.

The "Cyclone Underflow" is an excellent alumina product, and as a fireretardant would be considered a premium product.

The following table shows the complete analysis of the combined cycloneunderflow and centrifuge plus 5 micron products with the Al₂ O₃conventionally calculated.

    ______________________________________                                                Chemical Analysis - %                                                 % Wt.                                                                         Recovery  Al.sub.2 O.sub.3                                                                       SiO.sub.2                                                                             Fe.sub.2 O.sub.3                                                                     TiO.sub.2                                                                           L.O.I.                                ______________________________________                                        66.8      61.3     2.9     4.4    1.2   30.2                                  ______________________________________                                    

This is outstanding metallurgy with the high grade alumina concentrateproduced and a caustic soluble alumina recovery of approximately 90% ofthe originally contained caustic soluble alumina in the feed sample.

EXAMPLE 6

This example illustrates a preferred embodiment of the invention whereinthe raw material was ground in a laboratory rod mill using NaOH incombination with a dispersant; screened at 35 Tyler mesh with the plus35 mesh being only a trace and discarded and the minus 35 meshconditioned at a pH of 10.5 using NaOH as the alkaline agent; the pulpwas then subjected to three stages of high intensity magnetic separationto produce three magnetic concentrates and a nonmagnetic productcontaining in excess of 90% of the original aluminum bearing minerals.

The following were the test conditions:

The feed sample was a bauxite from South America and prepared aspreviously described.

A 600 gram charge was ground in a laboratory rod mill at 50% solids withthe addition of 3.0 ccs 10% NaOH solution and 3.0 ccs 21/2% Quebrachosolution. The pH at the end of grinding was 8.7. The pulp from the rodmill was screened on a 35 Tyler mesh with the plus 35 mesh containingmostly wood and rejected to waste.

The minus 35 mesh was transferred to a Wemco laboratory cell andconditioned for 15 minutes with the pH adjusted to 10.5 with NaOH. Thepulp was then subjected to three stages of magnetic separation using aColburn high intensity magnetic separator.

The following results were obtained:

    ______________________________________                                                    Chemical Analysis - %                                             Product       %                                                               Produced      Wt.     SiO.sub.2                                                                             Fe.sub.2 O.sub.3                                                                      TiO.sub.2                               ______________________________________                                        Mag. Conct. 1 6.3     1.2     43.1    3.0                                     Mag. Conct. 2 2.6     2.7     13.8    2.6                                     Mag. Conct. 3 1.6     4.0     8.2     2.2                                     Nonmagnetic Product                                                                         89.5    3.0     1.4     1.3                                     ______________________________________                                    

EXAMPLE 7

This example illustrates a preferred embodiment of the invention usingthe same raw material as in Example 6 and duplicating the same circuitwith the exception of using 4 ccs 10% NaOH solution to the laboratoryrod mill, raising the discharge pH to 10.5, and desliming thenonmagnetic product at about 10 microns using a laboratorythickener-sizer as the desliming equipment.

The following results were obtained with the three magnetic concentratesproduced combined and referred to as the magnetic concentrate, i.e.,"mag. conct.".

    ______________________________________                                                  Chemical Analysis - %                                               Product     %                                                                 Produced    Wt.      SiO.sub.2                                                                              Fe.sub.2 O.sub.3                                                                      TiO.sub.2                               ______________________________________                                        Mag. Conct. 10.1     1.8      31.3    2.8                                     Minus 10                                                                      Micron Product                                                                            34.5     2.9      3.1     1.7                                     Plus 10                                                                       Micron Product                                                                            55.4     2.7      0.8     1.2                                     ______________________________________                                    

The Mag. Conct., and the Minus 10 Micron Product are satisfactory feedto the Bayer Process and the Plus 10 Micron Product is outstanding and apremium product for use in the refractories industry.

EXAMPLE 8

This example illustrates a preferred embodiment of my invention withhigh intensity magnetic cobbing prior to desliming and followed by highintensity magnetic cobbing on the coarse fraction produced from thedesliming stage.

The ore sample used was a South American bauxite with a high ironcontent.

A 600 gram prepared sample of the material was ground in a laboratoryrod mill at 50% solids and with the addition of 6 ccs 10% NaOH solutionand 18 ccs. 21/2% Quebracho solution. The pH at the end of grinding was10.4. The pulp from the rod mill was screened on 35 Tyler mesh with theplus 35 mesh mainly wood particles and rejected as waste. The minus 35mesh was transferred to a laboratory sized Wembo flotation cell andconditioned for 15 minutes with the pH adjusted to 10.8 with NaOH.

The pulp was then subjected to three stages of high intensity magneticseparation using the Colbourn magnetic separator with the first magneticconcentrate kept separate, and hereafter referred to as mag. conct. 1,and the next two magnetic concentrates combined and hereafter referredto as mag. conct. 2. The nonmagnetic product produced was subjected todesliming at approximately 10 microns using a laboratory thickener-sizerapparatus to produce a plus 10 micron sized product and a minus 10micron sized product.

The plus 10 micron product was subjected to two stages of high intensitymagnetic separation using the Colburn magnetic separator with the twomagnetic concentrates produced combined and hereafter referred to asmag. conct. 3, and a final nonmagnetic product.

The following results were obtained:

    ______________________________________                                                 Chemical Analysis - %                                                Product    %                                                                  Produced   Wt.     Al.sub.2 O.sub.3                                                                      SiO.sub.2                                                                          Fe.sub.2 O.sub.3                                                                    TiO.sub.2                                                                          L.O.I.                             ______________________________________                                        Mag. Conct. 1                                                                            8.0     --      2.4  74.8  1.5  --                                 Mag. Conct. 2                                                                            5.8     --      2.5  44.9  1.9  --                                 Minus 10 Microns                                                                         25.4    --      15.1 27.4  5.2  --                                 Mag. Conct. 3                                                                            2.4     --      2.5  12.0  1.8  --                                 Nonmagnetics                                                                  Plus 10 Microns                                                                          58.4    63.1    1.7  1.8   0.8  32.6                               Calculated Head                                                               Sample Analysis                                                                          100.0   50.7    4.2  16.9  2.1  26.1                               ______________________________________                                    

The Mag. Conct. 1, Mag. Conct. 2, and the Minus 10 Micron Products wouldbe treated as waste. Mag. Conct. 3 would be satisfactory feed materialto the Bayer Process.

The Nonmagnetics Plus 10 Microns Product is outstanding as a product foruse in the chemical industry such as a premium grade fire retardant witha loss on ignition analysis of 32.6% as against a maximum possible ofapproximately 34.5%.

In one preferred embodiment of the invention, I use one or more stagesof desliming following my at least one stage of high intensity magneticseparation. However, dependent on the type of material and the circuitryused I may use one or more stages of desliming at any point in thecircuit following my dispersion-grinding stage.

Where I use a low to medium intensity magnetic stage or desliming orboth ahead of my at least one high intensity magnetic stage I can usethe at least one screening stage at any point in the circuit followingthe dispersion-grinding stage and prior to the at least one highintensity magnetic stage.

In my one at least high intensity magnetic stage the magnetic gap widthis in the range of about 0.35 millimeters to 2.0 millimeters. The widthof the gap is determined by measuring the closest distance betweenopposing ridges of north and south poles and is well understood in theart.

The invention has been described herein with reference to certainpreferred embodiments. However, as obvious variations thereon willbecome apparent to those skilled in the art, the invention is notconsidered to be limited thereto.

What is claimed is:
 1. A process for the upgrading of an aluminummineral bearing material selected from the group consisting of bauxitesand bauxitic clays comprising:(a) subjecting said material to at leastone stage of wet grinding at a pulp density of about 25% to 60% solids,and in the presence of at least sodium hydroxide, and in the pH range ofabout 8.5 to 12.5; (b) subsequently subjecting the said pulp to at leastone screening stage in the range of 10 mesh Tyler to 65 mesh Tyler toproduce a minus 10 to minus 65 mesh product, wherein the screen sizeused in said screening stage is a direct function of the width of themagnetic gap of a high intensity magnetic separation apparatus used in asubsequent at least one stage of high intensity magnetic separation; andwherein such screen size is at least 10% less in dimension than thewidth of the said magnetic gap setting in the subsequent at least onestage of high intensity magnetic separation; (c) subsequently subjectingthe said minus 10 to minus 65 mesh product to at least one stage of highintensity magnetic separation using a field strength of about 11.0 to22.0 kilogauss to produce a magnetic concentrate enriched in iron andtitanium ninerals and a nonmagnetic product impoverished in iron andtitanium minerals; and (d) subsequently subjecting said nonmagneticproduct to at least one stage of desliming to produce a fines productenriched in iron, titanium, and silica, and a coarse productimpoverished in iron, titanium and silica.
 2. A process according toclaim 1 wherein the said at least one stage of high intensity magneticseparation is carried out in a magnetic gap type high intensity magneticseparator.
 3. A process according to claim 1 wherein the said minus 10to minus 65 mesh product is subjected to at least two stages of highintensity magnetic separation in a magnetic gap type high intensitymagnetic separator.
 4. A process according to claim 1 wherein followingthe said desliming stage, the said coarse product produced issubsequently subjected to at least one stage of high intensity magneticseparation.
 5. A process according to claim 4 wherein the said at leastone stage of high intensity magnetic separation is carried out in amagnetic gap type high intensity magnetic separator.
 6. A process forthe upgrading of an aluminum mineral bearing material selected from thegroup consisting of bauxites and bauxitic clays comprising:(a)subjecting said material to at least one stage of wet grinding at a pulpdensity of about 25% to 60% solids, and in the presence of sodiumhydroxide alone and in the pH range of about 9.5 to 12.5; (b)subsequently subjecting the said pulp to at least one screening stage inthe range of 10 mesh Tyler to 65 mesh Tyler to produce a minus 10 tominus 65 mesh product, wherein the screen size used in said screeningstage is a direct function of the width of the magnetic gap of a highintensity magnetic separation apparatus used in a subsequent at leastone stage of high intensity magnetic separation; and wherein such screensize is at least 10% less in dimension than the width of the saidmagnetic gap setting in the subsequent at least one stage of highintensity magnetic separation; (c) subsequently subjecting said minus 10to minus 65 mesh product to at least one stage of high intensitymagnetic separation using a field strength of about 11.0 to 22.0kilogauss to produce a magnetic concentrate enriched in iron andtitanium minerals and a nonmagnetic product impoverished in iron andtitanium minerals; and (d) subsequently subjecting said nonmagneticproduct to at least one stage of desliming to produce a fines productenriched in iron, titanium, and silica, and a coarse productimpoverished in iron, titanium and silica.
 7. A process according toclaim 6 wherein the said at least one stage of high intensity magneticseparation is carried out in a magnetic gap type high intensity magneticseparator.
 8. A process according to claim 6 wherein the said minus 10to minus 65 mesh product is subjected to at least two stages of highintensity magnetic separation in a magnetic gap type high intensitymagnetic separator.
 9. A process according to claim 6 wherein followingthe said desliming stage, the said coarse product produced issubsequently subjected to at least one stage of high intensity magneticseparation.
 10. A process according to claim 9 wherein the said at leastone stage of said high intensity magnetic separation is carried out in amagnetic gap type high intensity magnetic separator.
 11. A process forthe upgrading of an aluminum mineral bearing material selected from thegroup consisting of bauxites and bauxitic clays comprising:(a)subjecting said material to at least one stage of wet grinding at a pulpdensity of about 25% to 60% solids, and in the presence of at leastsodium hydroxide, and an alkaline agent selected from the groupconsisting of KOH, NH₄ OH, Na₂ CO₃, and mixtures thereof and in the pHrange of about 9.5 to 12.5; (b) subsequently subjecting the said pulp toat least one screening stage in the range of 10 mesh Tyler to 65 meshTyler to produce a minus 10 to minus 65 mesh product, wherein the screensize used in said screening stage is a direct function of the width ofthe magnetic gap of a high intensity magnetic separation apparatus usedin a subsequent at least one stage of high intensity magneticseparation; and wherein such screen size is at least 10% less indimension than the width of the said magnetic gap setting in thesubsequent at least one stage of high intensity magnetic separation; (c)subsequently subjecting said minus 10 to minus 65 mesh product to atleast one stage of high intensity magnetic separation using a fieldstrength of about 11.0 to 22.0 kilogauss to produce a magneticconcentrate enriched in iron and titanium minerals and a nonmagneticproduct impoverished in iron and titanium minerals; and (d) subsequentlysubjecting said nonmagnetic product to at least one stage of deslimingto produce a fines product enriched in iron, titanium and silica, and acoarse product impoverished in iron, titanium and silica.
 12. A processaccording to claim 11 wherein the said at least one stage of highintensity magnetic separation is carried out in a magnetic gap type highintensity magnetic separator.
 13. A process according to claim 11wherein the said minus 10 to minus 65 mesh product is subjected to atleast two stages of high intensity magnetic separation in a magnetic gaptype high intensity magnetic separator.
 14. A process according to claim11 wherein following the said desliming stage, the said coarse productproduced is subsequently subjected to at least one stage of highintensity magnetic separation.
 15. A process according to claim 14wherein the said at least one stage of high intensity magneticseparation is carried out in a magnetic gap type high intensity magneticseparator.
 16. A process for the upgrading of an aluminum mineralbearing material selected from the group consisting of bauxites andbauxitic clays comprising:(a) subjecting said material to at least onestage of wet grinding at a pulp density of about 25% to 60% solids, andin the presence of at least sodium hydroxide, in combination with adispersant selected from the group consisting of lignins, silicates,phosphates, and mixtures thereof, and in the pH range of about 8.5 to12.5; (b) subsequently subjecting the said pulp to at least onescreening stage in the range of 10 mesh Tyler to 65 mesh Tyler toproduce a minus 10 to minus 65 mesh product, wherein the screen sizeused in said screening stage is a direct function of the width of themagnetic gap of a high intensity magnetic separation apparatus used in asubsequent at least one stage of high intensity magnetic separation; andwherein such screen size is at least 10% less in dimension than thewidth of the said magnetic gap setting in the subsequent at least onestage of high intensity magnetic separation; (c) subsequently subjectingsaid minus 10 to minus 65 mesh product to at least one stage of highintensity magnetic separation using a field strength of about 11.0 to22.0 kilogauss to produce a magnetic concentrate enriched in iron andtitanium minerals and a nonmagnetic product impoverished in iron andtitanium minerals; and (d) subsequently subjecting said nonmagneticproduct to at least one stage of desliming to produce a fines productenriched in iron, titanium, and silica, and a coarse productimpoverished in iron, titanium, and silica.
 17. A process according toclaim 16 wherein the said at least one stage of high intensity magneticseparation is carried out in a magnetic gap type high intensity magneticseparator.
 18. A process according to claim 16 wherein the said minus 10to minus 65 mesh product is subjected to at least two stages of highintensity magnetic separation in a magnetic gap type high intensitymagnetic separator.
 19. A process according to claim 16 whereinfollowing the said desliming stage, the said coarse product produced issubsequently subjected to at least one stage of high intensity magneticseparation.
 20. A process according to claim 19 wherein the said atleast one stage of high intensity magnetic separation is carried out ina magnetic gap type high intensity magnetic separator.
 21. A process forthe upgrading of an aluminum mineral bearing material selected from thegroup consisting of bauxites and bauxitic clays comprising:(a)subjecting said material to at least one stage of wet grinding at a pulpdensity of about 25% to 60% solids, and in the presence of at leastsodium hydroxide, in combination with an alkaline agent selected fromthe group consisting of KOH, NH₄ OH, Na₂ CO₃, and mixtures thereof, anda dispersant selected from the group consisting of lignins, silicates,phosphates, and mixtures thereof and in the pH range of about 8.5 to12.5; (b) subsequently subjecting the said pulp to at least onescreening stage in the range of 10 mesh Tyler to 65 mesh Tyler toproduce a 10 to minus 65 mesh product, wherein the screen size used insaid screening stage is a direct function of the width of the magneticgap of a high intensity magnetic separation apparatus used in asubsequent at least one stage of high intensity magnetic separation; andwherein such screen size is at least 10% less in dimension than thewidth of the said magnetic gap setting in the subsequent at least onestage of high intensity magnetic separation; (c) subsequently subjectingsaid minus 10 to minus 65 mesh product to at least one stage of highintensity magnetic separation using a field strength of about 11.0 to22.0 kilogauss to produce a magnetic concentrate enriched in iron andtitanium minerals and a nonmagnetic product impoverished in iron andtitanium minerals; and (d) subsequently subjecting said nonmagneticproduct to at least one stage of desliming to produce a fines productenriched in iron, titanium, and silica and a coarse product impoverishedin iron, titanium and silica.
 22. A process according to claim 21wherein the said at least one stage of high intensity magneticseparation is carried out in a magnetic gap type high intensity magneticseparator.
 23. A process according to claim 21 wherein the said minus 10to minus 65 mesh product is subjected to at least two stages of highintensity magnetic separation in a magnetic gap type high intensitymagnetic separator.
 24. A process according to claim 21 whereinfollowing the said desliming stage, the said coarse product produced issubsequently subjected to at least one stage of high intensity magneticseparation.
 25. A process according to claim 24 wherein the said atleast one stage of high intensity magnetic separation is carried out ina magnetic gap type high intensity magnetic separator.
 26. A process forthe upgrading of an aluminum mineral bearing material selected from thegroup consisting of bauxites and bauxitic clays comprising:(a)subjecting said materials to at least one stage of wet grinding at apulp density of about 25% to 60% solids, and in the presence of at leastsodium hydroxide and in the pH range of about 8.5 to 12.5; (b)subsequently subjecting the said pulp to at least one screening stage inthe range of 10 mesh Tyler to 65 mesh Tyler to produce a minus 10 tominus 65 mesh product, wherein the screen size used in said screeningstage is a direct function of the width of the magnetic gap of a highintensity magnetic separation apparatus used in a subsequent at leastone stage of high intensity magnetic separation; and wherein such screensize is at least 10% less in dimension than the width of the saidmagnetic gap setting in the subsequent at least one stage of highintensity magnetic separation; (c) subsequently subjecting said minus 10to minus 65 mesh product to at least one stage of low to mediumintensity magnetic separation in the range of 0.5 to 10.0 kilogauss toproduce a nonmagnetic product; (d) subsequently subjecting saidnonmagnetic product to at least one stage of high intensity magneticseparation using a field strength of about 11.0 to 22.0 kilogauss toproduce a magnetic concentrate enriched in iron and titanium mineralsand a nonmagnetic product impoverished in iron and titanium minerals;and (e) subsequently subjecting said nonmagnetic product to at least onestage of desliming to produce a fines product enriched in iron,titanium, and silica, and a coarse product impoverished in iron,titanium and silica.
 27. A process according to claim 26 wherein thesaid at least one stage of high intensity magnetic separation is carriedout in a magnetic gap type high intensity magnetic separator.
 28. Aprocess according to claim 26 wherein the said minus 10 to minus 65 meshproduct is subjected to at least two stages of high intensity magneticseparation in a magnetic gap type high intensity magnetic separator. 29.A process according to claim 26 wherein following the said deslimingstage, the said coarse product produced is subsequently subjected to atleast one stage of high intensity magnetic separation.
 30. A processaccording to claim 29 wherein the said at least one stage of highintensity magnetic separation is carried out in a magnetic gap type highintensity magnetic separator.
 31. A process according to claim 26wherein the said product is subjected to at least one screening stage inthe range of 10 mesh Tyler to 65 mesh Tyler to produce a minus 10 tominus 65 mesh product subsequent to the said at least one stage of lowto medium intensity magnetic separation.
 32. A process according toclaim 26 wherein the said non-magnetic product from (d) is subjected toat least two stages of desliming to produce a fines product enriched iniron, titanium, and silica and a coarse product impoverished in iron,titanium and silica.
 33. A process according to claim 26 wherein,subsequent to said at least one stage of wet grinding, and prior to saidat least one stage of high intensity magnetic separation, the saidproduct is subjected to at least one stage of desliming to produce afines product enriched in iron, titanium, and silica and a coarseproduct impoverished in iron, titanium, and silica.
 34. A process forthe upgrading of an aluminum mineral bearing material selected from thegroup consisting of bauxites and bauxitic clays comprising:(a)subjecting said material to at least one stage of wet grinding at a pulpdensity of about 25% to 60% solids, and in the presence of sodiumhydroxide and in the pH range of about 9.5 to 12.5; (b) subsequentlysubjecting the said pulp to at least one screening stage in the range of10 mesh Tyler to 65 mesh Tyler to produce a minus 10 to minus 65 meshproduct, wherein the screen size used in said screening stage is adirect function of the width of the magnetic gap of a high intensitymagnetic separation apparatus used in a subsequent at least one stage ofhigh intensity magnetic separation; and wherein such screen size is atleast 10% less in dimension than the width of the said magnetic gapsetting in the subsequent at least one stage of high intensity magneticseparation; (c) subsequently subjecting said minus 10 to minus 65 meshproduct to at least one stage of low to medium intensity magneticseparation in the range of 0.5 to 10.0 kilogauss to produce anonmagnetic product; (d) subsequently subjecting said nonmagneticproduct to at least one stage of high intensity magnetic separationusing a field strength of about 11.0 to 22.0 kilogauss to produce amagnetic concentrate enriched in iron and titanium minerals and anonmagnetic product impoverished in iron and titanium minerals; and (e)subsequently subjecting said nonmagnetic product to at least one stageof desliming to produce a fines product enriched in iron, titanium andsilica, and a coarse product impoverished an iron, titanium and silica.35. A process according to claim 34 wherein the said at least one stageof high intensity magnetic separation is carried out in a magnetic gaptype high intensity magnetic separator.
 36. A process according to claim34 wherein the said minus 10 to minus 65 mesh product is subjected to atleast two stages of high intensity magnetic separation in a magnetic gaptype high intensity magnetic separator.
 37. A process according to claim34 wherein following the said desliming stage, the said coarse productproduced is subsequently subjected to at least one stage of highintensity magnetic separation.
 38. A process according to claim 37wherein the said at least one stage of high intensity magneticseparation is carried out in a magnetic gap type high intensity magneticseparator.
 39. A process according to claim 34 wherein the said productis subjected to at least one screening stage in the range of 10 meshTyler to 65 mesh Tyler to produce a minus 10 to minus 65 mesh productsubsequent to the said at least one stage of low to medium intensitymagnetic separation.
 40. A process according to claim 34 wherein thesaid non-magnetic product from (d) is subjected to at least two stagesof desliming to produce a fines product enriched in iron, titanium andsilica and a coarse product impoverished in iron, titanium and silica.41. A process according to claim 40 wherein, subsequent to said at leastone stage of wet grinding, and prior to said at least one stage of highintensity magnetic separation, the said product is subjected to at leastone stage of desliming to produce a fines product enriched in iron,titanium and silica and a coarse product impoverished in iron, titaniumand silica.
 42. A process for the upgrading of an aluminum mineralbearing material selected from the group consisting of bauxites andbuaxitic clays comprising:(a) subjecting said material to at least onestage of wet grinding at a pulp density of about 25% to 60% solids, andin the presence of at least sodium hydroxide and an alkaline agentselected from the group consisting of KOH, NH₄ OH, Na₂ CO₃ and mixturesthereof and in the pH range of about 9.2 to 12.5; (b) subsequentlysubjecting the said pulp to at least one screening stage in the range of10 mesh Tyler to 65 mesh Tyler to produce a minus 10 to minus 65 meshproduct, wherein the screen size used in said screening stage is adirect function of the width of the magnetic gap of a high intensitymagnetic separation apparatus used in a subsequent at least one stage ofhigh intensity magnetic separation; and wherein such screen size is atleast 10% less in dimension than the width of the said magnetic gapsetting in the subsequent at least one stage of high intensity magneticseparation; (c) subsequently subjecting said minus 10 to minus 65 meshproduct to at least one stage of low to medium intensity magneticseparation in the range of 0.5 to 10.0 kilogauss to produce anonmagnetic product; (d) subsequently subjecting said nonmagneticproduct to at least one stage of high intensity magnetic separationusing a field strength of about 11.0 to 22.0 kilogauss to produce amagnetic concentrate enriched in iron and titanium minerals and anonmagnetic product impoverished in iron and titanium minerals; and (e)subsequently subjecting said nonmagnetic product to at least one stageof desliming to produce a fines product enriched in iron, titanium, andsilica, and a coarse product impoverished in iron, titanium and silica.43. A process according to claim 42 wherein the said at least one stageof high intensity magnetic separation is carried out in a magnetic gaptype high intensity magnetic separator.
 44. A process according to claim42 wherein the said minus 10 to minus 65 mesh product is subjected to atleast two stages of high intensity magnetic separation in a magnetic gaptype high intensity magnetic separator.
 45. A process according to claim42 wherein following the said desliming stage, the said coarse productproduced is subsequently subjected to at least one stage of highintensity magnetic separation.
 46. A process according to claim 45wherein the said at least one stage of high intensity magneticseparation is carried out in a magnetic type high intensity magneticseparator.
 47. A process according to claim 42 wherein the said productis subjected to at least one screening stage in the range of 10 meshTyler to 65 mesh Tyler to produce a minus 10 to minus 65 mesh productsubsequent to the said at least one stage of low to medium intensitymagnetic separation.
 48. A process according to claim 42 wherein thesaid non-magnetic product from (d) is subjected to at least two stagesof desliming to produce a fines product enriched in iron, titanium, andsilica and a coarse product impoverished in iron, titanium, and silica.49. A process according to claim 42 wherein, subsequent to said at leastone stage of wet grinding, and prior to said at least one stage of highintensity magnetic separation, the said product is subjected to at leastone stage of desliming to produce a fines product enriched in iron,titanium, and silica and a coarse product impoverished in iron, titaniumand silica.
 50. A process for the upgrading of an aluminum mineralbearing material selected from the group consisting of bauxites andbauxitic clays, comprising:(a) subjecting said material to at least onestage of wet grinding at a pulp density of about 25% to 60% solids, andin the presence of at least sodium hydroxide in combination with adispersant selected from the group consisting of lignins, silicates,phosphates and mixtures thereof and in the pH range of about 8.5 to12.5; (b) subsequently subjected and said pulp to at least one screeningstage in the range of 10 mesh Tyler to 65 mesh Tyler to produce a minus10 to minus 65 mesh product, wherein the screen size used in saidscreening stage is a direct function of the width of the magnetic gap ofa high intensity magnetic separation apparatus used in a subsequent atleast one stage of high intensity magnetic separation; and wherein suchscreen size is at least 10% less in dimension than the width of the saidmagnetic gap setting in the subsequent at least one stage of highintensity magnetic separation; (c) subsequently subjecting said minus 10to minus 65 mesh product to at least one stage of low to mediumintensity magnetic separation in the range of 0.5 to 10.0 kilogauss toproduce a nonmagnetic product; (d) subsequently subjecting saidnonmagnetic product to at least one stage of high intensity magneticseparation using a field strength of about 11.0 to 22.0 kilogauss toproduce a magnetic concentrate enriched in iron and titanium mineralsand a nonmagnetic product impoverished in iron and titanium minerals;and (e) subsequently subjecting said nonmagnetic product to at least onestage of desliming to produce a fines product enriched in iron, titaniumand silica, and a coarse product impoverished in iron, titanium andsilica.
 51. A process according to claim 50 wherein the said at leastone stage of high intensity magnetic separation is carried out in amagnetic gap type high intensity magnetic separator.
 52. A processaccording to claim 50 wherein the said minus 10 to minus 65 mesh productis subjected to at least two stages of high intensity magneticseparation in a magnetic gap type high intensity magnetic separator. 53.A process according to claim 50 wherein following the said deslimingstage, the said coarse product produced is subsequently subjected to atleast one stage of high intensity magnetic separation.
 54. A processaccording to claim 53 wherein the said at least one stage of highintensity magnetic separation is carried out in a magnetic gap type highintensity magnetic separator.
 55. A process according to claim 50wherein the said product is subjected to at least one screening stage inthe range of 10 mesh Tyler to 65 mesh Tyler to produce a minus 10 tominus 65 mesh product subsequent to the said at least one stage of lowto medium intensity magnetic separation.
 56. A process according toclaim 50 wherein the said non-magnetic product is subjected to at leasttwo stages of desliming to produce a fines produt enriched in iron,titanium and silica, and a coarse product impoverished in iron, titaniumand silica.
 57. A process according to claim 50 wherein, subsequent tosaid at least one stage of wet grinding, and prior to said at least onestage of high intensity magnetic separation, the said product issubjected to at least one stage of desliming to produce a fines productenriched in iron, titanium and silica, and a coarse product impoverishedin iron, titanium and silica.
 58. A process for the upgrading of analuminum mineral bearing material selected from the group consisting ofbauxites and bauxitic clays, comprising:(a) subjecting said material toat least one stage of wet grinding at a pulp density of about 25% to 60%solids, and in the presence of at least sodium hydroxide in combinationwith an alkaline agent selected from the group consisting of KOH, NH₄OH, Na₂ CO₃, and mixtures thereof, and a dispersant selected from thegroup consisting of lignins, silicates, phosphates and mixtures thereof,and in the pH range of about 8.5 to 12.5; (b) subsequently subjectingthe said pulp to at least one screening stage in the range of 10 meshTyler to 65 mesh Tyler to produce a minus 10 to minus 65 mesh product,wherein the screen size used in said screening stage is a directfunction of the width of the magnetic gap of a high intensity magneticseparation apparatus used in a subsequent at least one stage of highintensity magnetic separation; and wherein such screen size is at least10% less in dimension than the width of the said magnetic gap setting inthe subsequent at least one stage of high intensity magnetic separation;(c) subsequently subjecting said minus 10 to minus 65 mesh product to atleast one stage of low to medium intensity magnetic separation in therange of 0.5 to 10.0 kilogauss to produce a nonmagnetic product; (d)subsequently subjecting said nonmagnetic product to at least one stageof high intensity magnetic separation using a field strength of about11.0 to 22.0 kilogauss to produce a magnetic concentrate enriched iniron and titanium minerals and a nonmagnetic product impoverished iniron and titanium minerals; and (e) subsequently subjecting saidnonmagnetic product to at least one stage of desliming to produce afines product enriched in iron, titanium and silica, and a coarseproduct impoverished in iron, titanium and silica.
 59. A processaccording to claim 58 wherein the said at least one stage of highintensity magnetic separation is carried out in a magnetic gap type highintensity magnetic separator.
 60. A process according to claim 58wherein the said minus 10 to minus 65 mesh product is subjected to atleast two stages of high intensity magnetic separation in a magnetic gaptype high intensity magnetic separator.
 61. A process according to claim58 wherein following the said desliming stage, the said coarse productproduced is subsequently subjected to at least one stage of highintensity magnetic separation.
 62. A process according to claim 61wherein the said at least one stage of high intensity magneticseparation is carried out in a magnetic gap type high intensity magneticseparator.
 63. A process according to claim 58 wherein the said productis subjected to at least one screening stage in the range of 10 meshTyler to 65 mesh Tyler to produce a minus 10 to minus 65 mesh productsubsequent to the said at least one stage of low to medium intensitymagnetic separation.
 64. A process according to claim 58 wherein thesaid non-magnetic product from (d) is subjected to at least two stagesof desliming to produce a fines product enriched in iron, titanium andsilica and a coarse product impoverished in iron, titanium and silica.65. A process according to claim 58 wherein, subsequent to said at leastone stage of wet grinding, and prior to said at least one stage of highintensity magnetic separation, the said product is subjected to at leastone stage of desliming to produce a fines product enriched in iron,titanium and silica, and a coarse product impoverished in iron, titaniumand silica.